1 Project Summary Abstract 2 3 Otitis media (OM) is a major child health burden. Acute OM is the most commonly diagnosed pediatric 4 disease and the #1 reason for antimicrobial prescription to US children. Moreover, 62% of children with OM 5 demonstrate viral infections in their middle ear, to which antibiotics are ineffective but prescribed nonetheless. 6 The wide spread use of systemic antibiotics against a disease of such high prevalence and recurrence is 7 believed to breed antibiotic resistance. To avoid systemic antibiotic exposure, we developed a technology to 8 target the delivery of antibiotics directly to the middle ear. A crucial and practical feature of the delivery system 9 is a hydrogel, which is an easy-to-apply liquid at room temperature and gels quickly and firmly upon contacting 10 warm tympanic membrane (TM). Chemical permeation enhancers inside the gel can overcome the 11 impermeable barrier of the TM and bring antibiotics into the middle ear. A single application of the hydrogel 12 formulation provides enough antibiotics for a 7-day treatment. 13 The current application attempts to completely eliminate antibiotic usage in this prevalent childhood disease 14 and to mitigate OM-related antibiotic resistance by using a stand-alone therapy that treats both bacterial and 15 viral infections. 16 A key component of the K99 phase is to develop engineered nanoparticles that catalyze the conversion of 17 trace amount of ambient hydrogen peroxide to hypohalites. Hypohalites have broad-spectrum activity against 18 viruses, bacteria, and fungi. Importantly, some OM pathogens such as Streptococcus pneumoniae can produce 19 hydrogen peroxide, fueling the production of hypohalites by the nanoparticles. We thus hypothesized that the 20 nanoparticles can be used to treat OM, the treatment only commences in the presence of OM pathogens, and it 21 stops upon eradication of the infection. Therefore, a single application of the nanoparticles could treat recurrent 22 OM or be applied prophylactically. 23 The R00 phase of this application focuses on 1) demonstration of cure and prophylaxis of OM using a 24 stand-alone treatment for both viruses and bacteria; 2) understanding the effects of the nanomedicines on 25 pathogen-host interactions, biofilm formation, nasopharyngeal microbiome, and auditory physiology; 3) new 26 strategies to deliver nanoparticles across biological barriers in the ear. The non-invasively trans-tympanic 27 delivery of the nanoparticles will differ considerably from that of small molecules, which may require greater TM 28 permeability than can be achieved with our established technology. Based on our finding that inflamed TMs 29 have 10-15 times greater permeability than healthy ones, we hypothesized that inducing inflammation can 30 enhance permeation of nanoparticles. The knowledge and techniques developed during the R00 phase will 31 provide insight into the pathogenesis of acute and recurrent OM, which could be applied to direct the design of 32 next-generation therapeutics for the ear.